Starting Checkout on Home build.

[Emc]

Here's a little about what I have going on. A few months back I bought a 2-up 3d printer kit and put it together knowing that I wanted to be able to print on a much larger scale. Before producing a completed successful print (extrusion problems) I made the decision to build something that would satisfy my desire to go bigger and at the same time give me a more reliable platform.
I upped the size of the 'z' and 'y' motors to nema 23's and have micro switches for both ends of each axis. I got a couple of bowden extruders and an ep3 chimera hot end.

It took a bit but I have reached the point where I'm ready to start into control check-out. Using the ramps board (from the original 2-up) I turned the pots down on the drivers and powered up the board. I was able to control 'z' fairly well though it needs some mechanical tweeking, but have not got anything out of the other 2 axis yet. What I've been able to find about tuning the drivers (drivers rated at 2 amps and the 23's are rated 2.8 per coil) leaves me hesitant and wanting to reach out before I let the smoke out of something. I do have a thought for what might be a reasonable approach but would rather lean on some experience (This part of the process is what I have the most to learn about.)
It looks like my useful build-space when complete will be 24"x 22"x 13.5". It's a 'X/Z' head and 'Y' bed configuration.
Looking for suggestions to best proceed.
Emc

[printbus]

What I've been able to find about tuning the drivers (drivers rated at 2 amps and the 23's are rated 2.8 per coil) leaves me hesitant and wanting to reach out before I let the smoke out of something.

I don't have guidance to offer based on NEMA23 experience, but I'm curious what you've been able to find that has scared you off. Is it just that the information has been inconsistent, or something else? Having 2.8A motors with 2A drivers means you won't be able to drive the motors as hard as they are rated for, so the motors shouldn't be an issue. If you try to run the drivers too hard, the drivers will heat up and at some point will automatically stop driving the motor until the driver chip cools off a bit. Hopefully you have heatsinks and perhaps heatsink cooling airflow included in your approach.

The heftier motors (and associated higher current drive setting on the stepper drivers) will increase the 12V current draw on RAMPS. At some point you might be pushing the limit on the 5A current limit polyfuse on RAMPS, but if that happens the polyfuse opens, shutting down power to the electronics, with the polyfuse resetting after a bit.

It's hard to imagine a scenario that could lead to burning anything up.

Are you using the fifth stepper driver location for the 2nd Z motor or for a 2nd extruder? If both Z motors are in parallel on the same driver (a typical reprap approach), I would think that trying to drive two NEMA23 motors off one driver is pushing it. At best, your 2A driver could only be providing 1A to each 2.8A motor.

Again, I'm not speaking from NEMA23 experience.

[Emc]

Thanks for the reply.
I'll not be so hesitant in my efforts. I will tell you that I have only one 23 each for the 'Z' and 'Y' axis (5 steppers total for the build). It's definitely not conventional (no screws for 'Z' and no rods for 'Y'). I wasn't going to concentrate on the 2nd extruder until later. I did pick up an additional driver and jumpers for the 2nd extruder position. After I get everything running I'll take a couple of pics to see.
I'm sure that I'll have some additional questions as I move forward and become more familiar with this part of printing.

[printbus]

oh, my bad on the two z-motor thing. It'll be interesting to follow how having the single z-motor works with your wider print bed.